The Taiwanese Patent Serial Number 80215307, which has been approved and published for public inspection, discloses an improved push-button lock which comprises a locking rod of hollow construction and provided in the surface thereof with a slot and a lock hole. A first rod seat and a second rod seat, which are provided respectively with a retaining body, are fitted over the locking rod. An insertion pin is put through the first rod seat such that the insertion pin is located in the slot, thereby causing the locking rod to join with the first rod seat and to move axially in relation to the first rod seat. The locking rod is provided in the hollow interior thereof with an urging spring having two ends making contact respectively with the front end wall of the locking rod and the insertion pin. The second rod seat has a seat body provided with a small spring and a rod body. In the absence of an external force, the locking rod is urged by the urging spring to extend beyond one end of the outer sleeve of the lock. In the presence of an external force exerting on the locking rod which is therefore forced to move inwardly for a distance, the rod body of the second rod seat is inserted into the lock hole of the locking rod so as to bring about a locking effect.
The prior art locking device described above is defective in design in that the locking rod of a hollow construction is highly vulnerable to breakage, and that the first and the second rod seats are fitted movably over the locking rod before they are disposed in the outer sleeve, thereby making it rather time-consuming to mount various component parts, such as front retaining body, rear retaining body and small spring, in the openings of the first and the second rod seats.